Posts by PeakAtlas

Pimoroni PiGlow: Rainbow LED swirls for the Raspberry Pi

Re: @kiwimuso @James Hughes 1

Hi Kiwimuso,

I can understand the question about what the PiGlow is really for and also why someone would want one. However, I do "kind of" have a genuine use for it. Admittedly though, I was initially attracted to it simply because it's neat and pretty.

I now use mine to show the 100mS ticking of my task scheduler of a program that I've written on my Pi. A simple pattern is incremented on each step of the scheduler. The program looks after a variety of tasks including the control of some PIC based devices (that I've made myself), polling for emails, taking pictures with the raspi-cam and ftp tasks. All of those tasks can run without the monitor or keyboard being in the way. So a brief look at the PiGlow will tell me if the task scheduler is still running. If not, I know which task has caused an exception. I can then use a monitor and keyboard to do some further investigations or add some more exception handling as I slowly make the system more and more robust.

But ultimately it will be permanently "head-less" and I'll just rely on the PiGlow to be sure it's running just fine. Most of the time, the LEDs are on about 5% brightness, so it doesn't cause undue distraction in my study.

Cheers,

Jez

Re: There's no current leakage

Hi JeffyPoooh,

Yes, you are correct RGB LEDs can indeed be used to make white.

I guess I was referring to LEDs that are commonly known as "white LEDs", the only type that I've seen actually marketed (or advertised) as "white LEDs" are one's that are made with a blue LED under a phosphor. I could be wrong (I am frequently wrong), but that was my interpretation of the term "white LED". However, I do 100% agree with you that RGB LEDs (and indeed YB) can be used to make varieties of white light.

Forgive me if my original post didn't come across well, I wasn't making a criticism. The purpose of my post was to confirm what another poster had said, by experiment, that the white LEDs glowing when their neighboring blue LEDs were lit was not due to leakage current but by the same mechanism that causes common white LEDs to work.

There's no current leakage

As Indolent Wretch said, there is absolutely no current leakage between the white and blue LEDs. It is purely blue light hitting the phosphor coating in the white LEDs. I've confirmed that on my Piglow by 'shading' the lit blue LEDs with a tube (from a pen). Most tech savvy folk will be aware of this phenomenon, it's how white LEDs are made after all.